1. Field of the Invention
The present invention relates to a display method for a multimedia mobile terminal, and more particularly to a method for intelligently displaying a sports game video which enables a non-long-shot is to be displayed through an entire frame thereof, but a long-shot is to be displayed through an enlargement of only a Region Of Interest (ROI) existing therein, so that the long-shot includes objects are seen in a smaller scale.
2. Description of the Related Art
With the recent and rapid development of multimedia signal processing and transmission technology and the appearance of new types of mobile TV service including a Digital Video Broadcasting-Handheld (DVB)-H and Digital Multimedia Broadcasting (DMB), etc., the frequency of users watching videos through a small LCD panel is increasing. FIG. 1 is a diagram illustrating a state in which a DMB phone receives and outputs soccer game broadcasting. However, most services are simply provided in an existing screen size.
According to an experiment carried out by Knoche, etc., in order to measure conditions such as the number of pixels and a bit rate of an image suitable for displaying a reduced image on a mobile terminal (as published in “H. Knoche, J. D. McCarthy, and M. A. Sasse, Can small be beautiful?: assessing image resolution requirements for mobile TV, in MULTIMEDIA '05: Proceeding of the 13th annual ACM international conference on Multimedia, pp. 829-838, ACM Press, (New York, N.Y., USA), 2005”), it can be understood that a direct reduction of an image for display in a small terminal may cause loss of details. Such loss increases significantly when the content of an image is a field sport, particularly, a soccer video, which is reduced in a sequence of a music video, news and a cartoon video. Thus, it is desirable to develop intelligent display technology capable of allowing viewers of a small mobile terminal to view a screen including only an enlarged ROI. The ROI may be defined as a region in which users take a great interest on a screen or a region to which users pay much more attention than any other regions. As designation of the ROI may be a first step for meaningfully analyzing a video scene, it is important technology in the field of image analysis.
FIG. 2 is a diagram illustrating three types of shots existing in a sports game video. In FIG. 2, (a) indicates a long-shot, (b) indicates a medium-shot and (c) indicates a close-up shot. In long-shot (a), it is necessary to extract, enlarge and reproduce an ROI.
Various methods have been researched in order to determine an ROI. According to “L.ltti, C. Koch, and E. Niebur, A model of saliency-based visual attention for rapid scene analysis, IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 20. no. 11, pp. 1254-1259, November 1998.”, a visual attention model capable of expressing multiple spatial and visual features on one saliency map has been proposed in order to find out visually salient portions, but expansion to a moving picture has not been sufficiently considered.
According to “W.-H. Cheng, W.-T. Chu, and J.-L. Wu, A visual attention based region-of-interest determination framework for video sequences, IEICE Transactions on Information and Systems, E-88D, pp. 1578-1586, 2005.”, ROI determination in video has been researched based on brightness and darkness, color tone and motion information. In this research, they have proposed a method for indicating a most salient feature point in each image frame of video on an assumption that an important object has a high contrast in color tone or brightness and darkness. However, this assumption is not always correct because an important object may be dark or have a low contrast.
For video skimming and summary, according to “Y.-F. Ma and H.-J. Zhang, A model of motion attention for video skimming, in Proc, ICIP, pp, 129-132, 2002.”, a user's interest model has been proposed using motion, speech, camera operation, video edition information, etc., based on another video analysis method.
As described above, the methods for extracting ROIs by using considerable features within a video screen have proposed. However, a field sports video such as a soccer game includes both a shot requiring an extraction of an ROI and a shot not requiring the extraction of the ROI. In the former, small objects having considerable features simultaneously may exist within a screen. In this case, since multiple ROIs may exist, it is not suitable for intelligent display for a mobile terminal, which partially extracts the portions of a screen, then enlarges and displays the extracted portions.